The release of LH from the anterior pituitary is regulated by gonadotropin releasing hormone (GnRH). The cellular mechanism by which GnRH exerts its effect on LH release is not understood at the present time. Our results indicate that although cyclic AMP level in the tissue is increased by GnRH addition to pituitary incubation in vitro, it appears that the ability of GnRH to increase cAMP level is independent of its ability to cause LH release. The release process also appears to need metabolic energy as inhibitor of ATP production decreased the release of LH in response to GnRH. GnRH addition in vitro to pituitary cell cultures did enhance the incorporation of (3H) glucosamine into immunoprecipitable LH, but there was no apparent effect on the incorporation of amino acids into LH. We are currently investigating the turnover of proteins in the pituitary and the possible effect of GnRH on LH turnover. The possible existence of the precursor protein for LH is also under investigation.